Some types of error correction codes, such as Low Density Parity Check (LDPC) and Quasi-Cyclic (QC)-LDPC codes, are commonly decoded using iterative decoding processes. Various schemes for iterative decoding are known in the art. For example, in U.S. Pat. No. 8,645,810, whose disclosure is incorporated herein by reference, a termination indication is computed during an iteration of an iterative decoding of a representation of a codeword according to a schedule. The termination indication is tested to see if the decoding has converged or is not likely to converge. The testing of the termination indication shows convergence or lack of likelihood thereof even if a codeword bit estimate was flipped during an immediately preceding traversal of the schedule. Preferably, the termination indication includes an error correction syndrome weight, a zero value whereof indicates convergence, and the computing of the termination indication includes, in response to the flipping of a codeword bit estimate, flipping the error correction syndrome bits that are influenced by that codeword bit estimate.
U.S. Pat. No. 8,661,326, whose disclosure is incorporated herein by reference, describes a decoding system including a low density parity check (LDPC) processing module and a termination module. The LDPC processing module is configured to receive a test codeword based on a codeword received over a communications channel, and to perform, for each row of a parity-check matrix, a processing operation on the test codeword. The LDPC processing module is configured to, once the processing operations have been performed for all the rows, repeat the processing operations. The termination module is configured to monitor progress of the LDPC processing module and selectively generate a termination signal in response to the test codeword being a valid codeword according to the parity-check matrix. The LDPC processing module is further configured to terminate the processing operations in response to generation of the termination signal.
U.S. Patent Application Publication 2015/0249471, whose disclosure is incorporated herein by reference, describes a method and a decoder for early terminating decoding processes of serial concatenated coding. The method includes the steps of: A) providing a codeword, encoded by a first coding and a second coding sequentially, decoding of the second coding needing iterative calculations for syndromes; B) setting a maximum syndrome weight; C) processing decoding of the second coding for the codeword; D) terminating decoding of the second coding if a number of the iterative calculations reaches a preset number or a syndrome weight of one iterative calculation is equal to or smaller than the maximum syndrome weight, otherwise repeating step C to step D; and E) decoding the first coding for the codeword.